17
YELLOWSTONE EXPEDITION OF 1870
there are a dozen caldrons of grayish clay mud, varying
from 6 to 40 feet in diameter, and from 3 to 10 feet in depth, each with
its vent of sulphur vapor and slimy crater, from 3 to 5 feet in height.
Just above camp the bed of the river is full of hot-water spouts, with
bubbles of gas escaping. In a ravine, over the ridge, hot vapors pour out
in every direction, and here is a remarkable group. A small stream of green
water flows down the ravine, having its source in a rocky cave in the bank,
with an aperture of 6 by 8 feet -- a perfect grotto, lined with brilliant
metallic tints of green, red, and black, from which steam escapes in regular
pulsations to a distance of 40 feet, forcing out the water in waves, which
break over an outside horizontal rim, about once in ten seconds. A few
yards further down are several boiling springs of yellow muddy-water, the
largest of which is 80 feet in diameter, through which the vapor rushes
with a loud hissing sound. One hundred yards from the bank of the river,
and below these springs, is a geyser of dark muddy water; its basin is
200 feet across on the outer rim, and about 6 feet deep, with a channel
cut through one side for the passage of flood water from the hills. The
area is floored with a strata of mud rock, deposited from the water, forming
a circular plateau, in the middle of which is an oblong crater, 45 by 75
feet, with an irregular vapor vent, and system of steam jets adjoining,
covering the whole space to the outer rim on the right. This was a periodic
geyser, having eruptions every six hours, and in the following manner:
The crater being full of boiling water, and the vapor vent active, suddenly
columns of steam shoot up through the water to the height of 300 feet.
The ground trembles, the vapor hisses through the vent with increased force.
The water of the crater is violently agitated, being thrown up in vast
columns, to the height of 30 and 40 feet, splashing out as far as the rim
of the basin with great force. This continues for half an hour, the water
increasing in quantity in the crater all the while. Then the steam ceases
suddenly to escape, the water settles, and commences to lower in the crater,
continuing to fall to the depth of 35 feet, leaving bare the incrusted
and funnel-shaped walls, which converge at that depth to the diameter of
7 feet. The water here stands for a time, the steam jets cease to hiss,
the vapor vent to give forth its fumes, and all is quiet. After the lapse
of an hour, the water stoutly rises again, the vents become active, and
at the end of the regular period the whole performance is repeated as before.
A few hundred yards from here is an object of
the greatest interest. On the slope of a small and steep wooded ravine
is the crater of a mud volcano, 30 feet in diameter at the rim, which is
elevated a few feet above the surface on the lower side, and bounded by
the slope of the hill of the upper, converging, as it deepens, to the diameter
of 15 feet at the lowest visible point, about 40 feet down. Heavy volumes
of steam escape from this opening, ascending to the height of 300 feet.
From far down in the earth came a jarring sound, in regular beats of five
seconds, with a concussion that shook the ground at two hundred yards distant.
After each concussion came a splash of mud, as if thrown to a great height;
sometimes it could be seen from the edge of the crater, but none was entirely
ejected while we were there. Occasionally an explosion was heard like the
bursting of heavy guns behind an embankment, and causing the earth to tremble
for a mile around. These explosions were accompanied by a vast increase
of the volumes of steam poured forth from the crater. This volcano has
not been long in operation, as young pines, crushed flat to the earth under
the rim of mud, were still alive at the tops. The amount of matter ejected
was not great, con- Go
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